30-04-2019, 01:53 PM
I run transverters on my IC-706 series transceiver and have turned the output power back using the RF Power adjustment and haven't (yet) damaged any of my transverters. My preferred method for power control - and used extensively by me in the past - has been to put an external negative voltage on the ALC connector pin and use a potentiometer (/trimpot) to set the actual applied voltage. The required voltage for my radio has been about -3V so a zero to -5V is supply adequate.
The setup process is to set the RF Power to say 2-3 watts without the ALC connection in place, then connect the negative ALC control voltage and adjust the RF power to 1.5-2 watts. (Ideally you set it to -5V first and reduce the voltage and see the output power rise to 2W.) That means the external voltage actually controls the output power regardless of whether you remember to reduce the RF Power setting next time around and whether ALC overshoot or undershoot actually occurs.
You can get the negative voltage from the likes of an ICL7660 voltage generator IC plus a few extra components (a 5V 3-terminal 100mA (or more) regulator plus a few electrolytic capacitors and a trimpot to set the output voltage) but here is the key point : the negative voltage generator is powered the whole time, both on transmit and receive, and connected to the ALC control pin the whole time.
Have fun on 1296 !!
The setup process is to set the RF Power to say 2-3 watts without the ALC connection in place, then connect the negative ALC control voltage and adjust the RF power to 1.5-2 watts. (Ideally you set it to -5V first and reduce the voltage and see the output power rise to 2W.) That means the external voltage actually controls the output power regardless of whether you remember to reduce the RF Power setting next time around and whether ALC overshoot or undershoot actually occurs.
You can get the negative voltage from the likes of an ICL7660 voltage generator IC plus a few extra components (a 5V 3-terminal 100mA (or more) regulator plus a few electrolytic capacitors and a trimpot to set the output voltage) but here is the key point : the negative voltage generator is powered the whole time, both on transmit and receive, and connected to the ALC control pin the whole time.
Have fun on 1296 !!
Doug VK4ADC @ QG62LG51
http://www.vk4adc.com
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http://www.vk4adc.com
This Forum is only going to be as interesting as the posts it contains.
If you have a comment or question, post it as it may trigger or answer the query in someone else's mind.